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Commit 64f638c7 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: fix the race while wakeup all pv guest 



In kvm_async_pf_wakeup_all(), we add a dummy apf to vcpu->async_pf.done
without holding vcpu->async_pf.lock, it will break if we are handling apfs
at this time.

Also use 'list_empty_careful()' instead of 'list_empty()'

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 15096ffc

virt/kvm/async_pf.c

+4 −1
Original line number Diff line number Diff line
@@ -196,7 +196,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 
{

	struct kvm_async_pf *work;



	if (!list_empty(&vcpu->async_pf.done))

	if (!list_empty_careful(&vcpu->async_pf.done))

		return 0;



	work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
@@ -207,7 +207,10 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 
	get_page(bad_page);

	INIT_LIST_HEAD(&work->queue); /* for list_del to work */



	spin_lock(&vcpu->async_pf.lock);

	list_add_tail(&work->link, &vcpu->async_pf.done);

	spin_unlock(&vcpu->async_pf.lock);



	vcpu->async_pf.queued++;

	return 0;

}